Beta-blockade with nebivolol enhances the acetylcholine-induced cutaneous vasodilation

Nebivolol is a selective beta(1)-adrenoceptor blocker that has a vasorelaxa nt activity thought to be the result of a facilitation of the release of ni tric oxide from the endothelium. This study was undertaken in 12 healthy ma le volunteers to assess whether this compound increases the vasodilatory re sponse to acetylcholine when administered orally at a dose commonly recomme nded for the treatment of cardiovascular diseases. The subjects were random ly allocated to an 8-day treatment with nebivolol(5 mg once a day) and aten olol (50 mg once a day) according to a cross-over design. The two treatment s were separated by a 1-week washout period. On the first and the last day of each treatment phase, both before drug administration and 3 hours after drug administration, the forearm skin blood flow response to acetylcholine applied by iontophoresis was determined with the use of a laser Doppler sca nner imaging system. The reactivity to acetylcholine was significantly incr eased 3 hours after the administration of nebivolol on both the first and t he last day of treatment, whereas atenolol had no effect on this parameter. These data therefore indicate that nebivolol, but not atenolol, enhances t he vasorelaxant activity of acetylcholine in the skin vascular bed; this is compatible with a facilitation by this beta-blocker of the endothelium-dep endent vasodilation.